ff is a finite field library written in pure Rust, with no unsafe{} code.

This crate follows the zkcrypto RFC process. If you want to propose "substantial" changes to this crate (in particular to the ff traits), please create an RFC for wider discussion.

• This library does not provide constant-time guarantees. The traits enable downstream users to expose constant-time logic, but #[derive(PrimeField)] in particular does not generate constant-time code (even for trait methods that return constant-time-compatible values).

Add the ff crate to your Cargo.toml:

[dependencies]
ff = "0.13"

The ff crate contains the Field and PrimeField traits. See the documentation for more.

If you need an implementation of a prime field, this library also provides a procedural macro that will expand into an efficient implementation of a prime field when supplied with the modulus. PrimeFieldGenerator must be an element of Fp of p-1 order, that is also quadratic nonresidue.

First, enable the derive crate feature:

[dependencies]
ff = { version = "0.13", features = ["derive"] }

And then use the macro like so:

#[macro_use]
extern crate ff;

#[derive(PrimeField)]
#[PrimeFieldModulus = "52435875175126190479447740508185965837690552500527637822603658699938581184513"]
#[PrimeFieldGenerator = "7"]
#[PrimeFieldReprEndianness = "little"]
struct Fp([u64; 4]);

And that's it! Fp now implements Field and PrimeField.

Requires Rust 1.56 or higher.

Minimum supported Rust version can be changed in the future, but it will be done with a minor version bump.

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.